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5e28c532 | 1 | /* |
abc490a1 MD |
2 | * rculfhash.c |
3 | * | |
1475579c | 4 | * Userspace RCU library - Lock-Free Resizable RCU Hash Table |
abc490a1 MD |
5 | * |
6 | * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
0dcf4847 | 7 | * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com> |
abc490a1 MD |
8 | * |
9 | * This library is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU Lesser General Public | |
11 | * License as published by the Free Software Foundation; either | |
12 | * version 2.1 of the License, or (at your option) any later version. | |
13 | * | |
14 | * This library is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | * Lesser General Public License for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU Lesser General Public | |
20 | * License along with this library; if not, write to the Free Software | |
21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
5e28c532 MD |
22 | */ |
23 | ||
e753ff5a MD |
24 | /* |
25 | * Based on the following articles: | |
26 | * - Ori Shalev and Nir Shavit. Split-ordered lists: Lock-free | |
27 | * extensible hash tables. J. ACM 53, 3 (May 2006), 379-405. | |
28 | * - Michael, M. M. High performance dynamic lock-free hash tables | |
29 | * and list-based sets. In Proceedings of the fourteenth annual ACM | |
30 | * symposium on Parallel algorithms and architectures, ACM Press, | |
31 | * (2002), 73-82. | |
32 | * | |
1475579c | 33 | * Some specificities of this Lock-Free Resizable RCU Hash Table |
e753ff5a MD |
34 | * implementation: |
35 | * | |
36 | * - RCU read-side critical section allows readers to perform hash | |
37 | * table lookups and use the returned objects safely by delaying | |
38 | * memory reclaim of a grace period. | |
39 | * - Add and remove operations are lock-free, and do not need to | |
40 | * allocate memory. They need to be executed within RCU read-side | |
41 | * critical section to ensure the objects they read are valid and to | |
42 | * deal with the cmpxchg ABA problem. | |
43 | * - add and add_unique operations are supported. add_unique checks if | |
44 | * the node key already exists in the hash table. It ensures no key | |
45 | * duplicata exists. | |
46 | * - The resize operation executes concurrently with add/remove/lookup. | |
47 | * - Hash table nodes are contained within a split-ordered list. This | |
48 | * list is ordered by incrementing reversed-bits-hash value. | |
1ee8f000 | 49 | * - An index of bucket nodes is kept. These bucket nodes are the hash |
e753ff5a MD |
50 | * table "buckets", and they are also chained together in the |
51 | * split-ordered list, which allows recursive expansion. | |
1475579c MD |
52 | * - The resize operation for small tables only allows expanding the hash table. |
53 | * It is triggered automatically by detecting long chains in the add | |
54 | * operation. | |
55 | * - The resize operation for larger tables (and available through an | |
56 | * API) allows both expanding and shrinking the hash table. | |
4c42f1b8 | 57 | * - Split-counters are used to keep track of the number of |
1475579c | 58 | * nodes within the hash table for automatic resize triggering. |
e753ff5a MD |
59 | * - Resize operation initiated by long chain detection is executed by a |
60 | * call_rcu thread, which keeps lock-freedom of add and remove. | |
61 | * - Resize operations are protected by a mutex. | |
62 | * - The removal operation is split in two parts: first, a "removed" | |
63 | * flag is set in the next pointer within the node to remove. Then, | |
64 | * a "garbage collection" is performed in the bucket containing the | |
65 | * removed node (from the start of the bucket up to the removed node). | |
66 | * All encountered nodes with "removed" flag set in their next | |
67 | * pointers are removed from the linked-list. If the cmpxchg used for | |
68 | * removal fails (due to concurrent garbage-collection or concurrent | |
69 | * add), we retry from the beginning of the bucket. This ensures that | |
70 | * the node with "removed" flag set is removed from the hash table | |
71 | * (not visible to lookups anymore) before the RCU read-side critical | |
72 | * section held across removal ends. Furthermore, this ensures that | |
73 | * the node with "removed" flag set is removed from the linked-list | |
5c4ca589 MD |
74 | * before its memory is reclaimed. After setting the "removal" flag, |
75 | * only the thread which removal is the first to set the "removal | |
76 | * owner" flag (with an xchg) into a node's next pointer is considered | |
77 | * to have succeeded its removal (and thus owns the node to reclaim). | |
78 | * Because we garbage-collect starting from an invariant node (the | |
79 | * start-of-bucket bucket node) up to the "removed" node (or find a | |
80 | * reverse-hash that is higher), we are sure that a successful | |
81 | * traversal of the chain leads to a chain that is present in the | |
82 | * linked-list (the start node is never removed) and that is does not | |
83 | * contain the "removed" node anymore, even if concurrent delete/add | |
84 | * operations are changing the structure of the list concurrently. | |
85 | * - The add operation performs garbage collection of buckets if it | |
29e669f6 MD |
86 | * encounters nodes with removed flag set in the bucket where it wants |
87 | * to add its new node. This ensures lock-freedom of add operation by | |
88 | * helping the remover unlink nodes from the list rather than to wait | |
89 | * for it do to so. | |
e753ff5a MD |
90 | * - A RCU "order table" indexed by log2(hash index) is copied and |
91 | * expanded by the resize operation. This order table allows finding | |
1ee8f000 LJ |
92 | * the "bucket node" tables. |
93 | * - There is one bucket node table per hash index order. The size of | |
94 | * each bucket node table is half the number of hashes contained in | |
93d46c39 | 95 | * this order (except for order 0). |
1ee8f000 LJ |
96 | * - synchronzie_rcu is used to garbage-collect the old bucket node table. |
97 | * - The per-order bucket node tables contain a compact version of the | |
e753ff5a MD |
98 | * hash table nodes. These tables are invariant after they are |
99 | * populated into the hash table. | |
93d46c39 | 100 | * |
0f5543cb MD |
101 | * Linearizability Guarantees: |
102 | * | |
103 | * To discuss these guarantees, we first define "read" operations as any | |
104 | * of the following operations surrounded by an RCU read-side lock/unlock | |
105 | * pair: | |
106 | * - cds_lfht_lookup | |
107 | * - cds_lfht_lookup followed by iteration with cds_lfht_next_duplicate | |
108 | * - cds_lfht_first followed iteration with cds_lfht_next | |
109 | * | |
110 | * We define "write" operations as any of cds_lfht_add, | |
111 | * cds_lfht_add_unique, cds_lfht_add_replace, cds_lfht_del. | |
112 | * | |
113 | * The following guarantees are offered by this hash table: | |
114 | * | |
115 | * A) "read" after "write" will always return the result of the latest | |
116 | * write. | |
117 | * B) "write" after "read" will never be returned by the read. | |
118 | * C) It is guaranteed that after a grace period following a "del" and | |
119 | * "replace" operation, no reference to the removed items exists in | |
120 | * the hash table. | |
121 | * D) Uniqueness guarantee: when using add_unique and/or add_replace to | |
122 | * insert nodes into the table, if there was previously one node or | |
123 | * less with the same key being inserted by one or more concurrent | |
124 | * add_unique and/or add_replace, all concurrent "read" performed on | |
125 | * the hash table are guaranteed to find one, and only one node with | |
126 | * that key. | |
127 | * | |
1ee8f000 | 128 | * Bucket node tables: |
93d46c39 | 129 | * |
1ee8f000 LJ |
130 | * hash table hash table the last all bucket node tables |
131 | * order size bucket node 0 1 2 3 4 5 6(index) | |
93d46c39 LJ |
132 | * table size |
133 | * 0 1 1 1 | |
134 | * 1 2 1 1 1 | |
135 | * 2 4 2 1 1 2 | |
136 | * 3 8 4 1 1 2 4 | |
137 | * 4 16 8 1 1 2 4 8 | |
138 | * 5 32 16 1 1 2 4 8 16 | |
139 | * 6 64 32 1 1 2 4 8 16 32 | |
140 | * | |
1ee8f000 | 141 | * When growing/shrinking, we only focus on the last bucket node table |
93d46c39 LJ |
142 | * which size is (!order ? 1 : (1 << (order -1))). |
143 | * | |
144 | * Example for growing/shrinking: | |
1ee8f000 LJ |
145 | * grow hash table from order 5 to 6: init the index=6 bucket node table |
146 | * shrink hash table from order 6 to 5: fini the index=6 bucket node table | |
93d46c39 | 147 | * |
1475579c MD |
148 | * A bit of ascii art explanation: |
149 | * | |
150 | * Order index is the off-by-one compare to the actual power of 2 because | |
151 | * we use index 0 to deal with the 0 special-case. | |
152 | * | |
153 | * This shows the nodes for a small table ordered by reversed bits: | |
154 | * | |
155 | * bits reverse | |
156 | * 0 000 000 | |
157 | * 4 100 001 | |
158 | * 2 010 010 | |
159 | * 6 110 011 | |
160 | * 1 001 100 | |
161 | * 5 101 101 | |
162 | * 3 011 110 | |
163 | * 7 111 111 | |
164 | * | |
165 | * This shows the nodes in order of non-reversed bits, linked by | |
166 | * reversed-bit order. | |
167 | * | |
168 | * order bits reverse | |
169 | * 0 0 000 000 | |
0adc36a8 LJ |
170 | * 1 | 1 001 100 <- |
171 | * 2 | | 2 010 010 <- | | |
f6fdd688 | 172 | * | | | 3 011 110 | <- | |
1475579c MD |
173 | * 3 -> | | | 4 100 001 | | |
174 | * -> | | 5 101 101 | | |
175 | * -> | 6 110 011 | |
176 | * -> 7 111 111 | |
e753ff5a MD |
177 | */ |
178 | ||
2ed95849 | 179 | #define _LGPL_SOURCE |
125f41db | 180 | #define _GNU_SOURCE |
2ed95849 | 181 | #include <stdlib.h> |
e0ba718a MD |
182 | #include <errno.h> |
183 | #include <assert.h> | |
184 | #include <stdio.h> | |
abc490a1 | 185 | #include <stdint.h> |
f000907d | 186 | #include <string.h> |
125f41db | 187 | #include <sched.h> |
e0ba718a | 188 | |
15cfbec7 | 189 | #include "config.h" |
2ed95849 | 190 | #include <urcu.h> |
abc490a1 | 191 | #include <urcu-call-rcu.h> |
7b17c13e | 192 | #include <urcu-flavor.h> |
a42cc659 MD |
193 | #include <urcu/arch.h> |
194 | #include <urcu/uatomic.h> | |
a42cc659 | 195 | #include <urcu/compiler.h> |
abc490a1 | 196 | #include <urcu/rculfhash.h> |
0b6aa001 | 197 | #include <rculfhash-internal.h> |
5e28c532 | 198 | #include <stdio.h> |
464a1ec9 | 199 | #include <pthread.h> |
44395fb7 | 200 | |
f8994aee | 201 | /* |
4c42f1b8 | 202 | * Split-counters lazily update the global counter each 1024 |
f8994aee MD |
203 | * addition/removal. It automatically keeps track of resize required. |
204 | * We use the bucket length as indicator for need to expand for small | |
205 | * tables and machines lacking per-cpu data suppport. | |
206 | */ | |
207 | #define COUNT_COMMIT_ORDER 10 | |
4ddbb355 | 208 | #define DEFAULT_SPLIT_COUNT_MASK 0xFUL |
6ea6bc67 MD |
209 | #define CHAIN_LEN_TARGET 1 |
210 | #define CHAIN_LEN_RESIZE_THRESHOLD 3 | |
2ed95849 | 211 | |
cd95516d | 212 | /* |
76a73da8 | 213 | * Define the minimum table size. |
cd95516d | 214 | */ |
d0d8f9aa LJ |
215 | #define MIN_TABLE_ORDER 0 |
216 | #define MIN_TABLE_SIZE (1UL << MIN_TABLE_ORDER) | |
cd95516d | 217 | |
b7d619b0 | 218 | /* |
1ee8f000 | 219 | * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink. |
b7d619b0 | 220 | */ |
6083a889 MD |
221 | #define MIN_PARTITION_PER_THREAD_ORDER 12 |
222 | #define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER) | |
b7d619b0 | 223 | |
d95bd160 MD |
224 | /* |
225 | * The removed flag needs to be updated atomically with the pointer. | |
48ed1c18 | 226 | * It indicates that no node must attach to the node scheduled for |
b198f0fd | 227 | * removal, and that node garbage collection must be performed. |
1ee8f000 | 228 | * The bucket flag does not require to be updated atomically with the |
d95bd160 MD |
229 | * pointer, but it is added as a pointer low bit flag to save space. |
230 | */ | |
d37166c6 | 231 | #define REMOVED_FLAG (1UL << 0) |
1ee8f000 | 232 | #define BUCKET_FLAG (1UL << 1) |
db00ccc3 MD |
233 | #define REMOVAL_OWNER_FLAG (1UL << 2) |
234 | #define FLAGS_MASK ((1UL << 3) - 1) | |
d37166c6 | 235 | |
bb7b2f26 | 236 | /* Value of the end pointer. Should not interact with flags. */ |
f9c80341 | 237 | #define END_VALUE NULL |
bb7b2f26 | 238 | |
7f52427b MD |
239 | /* |
240 | * ht_items_count: Split-counters counting the number of node addition | |
241 | * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag | |
242 | * is set at hash table creation. | |
243 | * | |
244 | * These are free-running counters, never reset to zero. They count the | |
245 | * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER) | |
246 | * operations to update the global counter. We choose a power-of-2 value | |
247 | * for the trigger to deal with 32 or 64-bit overflow of the counter. | |
248 | */ | |
df44348d | 249 | struct ht_items_count { |
860d07e8 | 250 | unsigned long add, del; |
df44348d MD |
251 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
252 | ||
7f52427b MD |
253 | /* |
254 | * rcu_resize_work: Contains arguments passed to RCU worker thread | |
255 | * responsible for performing lazy resize. | |
256 | */ | |
abc490a1 MD |
257 | struct rcu_resize_work { |
258 | struct rcu_head head; | |
14044b37 | 259 | struct cds_lfht *ht; |
abc490a1 | 260 | }; |
2ed95849 | 261 | |
7f52427b MD |
262 | /* |
263 | * partition_resize_work: Contains arguments passed to worker threads | |
264 | * executing the hash table resize on partitions of the hash table | |
265 | * assigned to each processor's worker thread. | |
266 | */ | |
b7d619b0 | 267 | struct partition_resize_work { |
1af6e26e | 268 | pthread_t thread_id; |
b7d619b0 MD |
269 | struct cds_lfht *ht; |
270 | unsigned long i, start, len; | |
271 | void (*fct)(struct cds_lfht *ht, unsigned long i, | |
272 | unsigned long start, unsigned long len); | |
273 | }; | |
274 | ||
abc490a1 MD |
275 | /* |
276 | * Algorithm to reverse bits in a word by lookup table, extended to | |
277 | * 64-bit words. | |
f9830efd | 278 | * Source: |
abc490a1 | 279 | * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable |
f9830efd | 280 | * Originally from Public Domain. |
abc490a1 MD |
281 | */ |
282 | ||
283 | static const uint8_t BitReverseTable256[256] = | |
2ed95849 | 284 | { |
abc490a1 MD |
285 | #define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64 |
286 | #define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16) | |
287 | #define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 ) | |
288 | R6(0), R6(2), R6(1), R6(3) | |
289 | }; | |
290 | #undef R2 | |
291 | #undef R4 | |
292 | #undef R6 | |
2ed95849 | 293 | |
abc490a1 MD |
294 | static |
295 | uint8_t bit_reverse_u8(uint8_t v) | |
296 | { | |
297 | return BitReverseTable256[v]; | |
298 | } | |
ab7d5fc6 | 299 | |
abc490a1 MD |
300 | static __attribute__((unused)) |
301 | uint32_t bit_reverse_u32(uint32_t v) | |
302 | { | |
303 | return ((uint32_t) bit_reverse_u8(v) << 24) | | |
304 | ((uint32_t) bit_reverse_u8(v >> 8) << 16) | | |
305 | ((uint32_t) bit_reverse_u8(v >> 16) << 8) | | |
306 | ((uint32_t) bit_reverse_u8(v >> 24)); | |
2ed95849 MD |
307 | } |
308 | ||
abc490a1 MD |
309 | static __attribute__((unused)) |
310 | uint64_t bit_reverse_u64(uint64_t v) | |
2ed95849 | 311 | { |
abc490a1 MD |
312 | return ((uint64_t) bit_reverse_u8(v) << 56) | |
313 | ((uint64_t) bit_reverse_u8(v >> 8) << 48) | | |
314 | ((uint64_t) bit_reverse_u8(v >> 16) << 40) | | |
315 | ((uint64_t) bit_reverse_u8(v >> 24) << 32) | | |
316 | ((uint64_t) bit_reverse_u8(v >> 32) << 24) | | |
317 | ((uint64_t) bit_reverse_u8(v >> 40) << 16) | | |
318 | ((uint64_t) bit_reverse_u8(v >> 48) << 8) | | |
319 | ((uint64_t) bit_reverse_u8(v >> 56)); | |
320 | } | |
321 | ||
322 | static | |
323 | unsigned long bit_reverse_ulong(unsigned long v) | |
324 | { | |
325 | #if (CAA_BITS_PER_LONG == 32) | |
326 | return bit_reverse_u32(v); | |
327 | #else | |
328 | return bit_reverse_u64(v); | |
329 | #endif | |
330 | } | |
331 | ||
f9830efd | 332 | /* |
24365af7 MD |
333 | * fls: returns the position of the most significant bit. |
334 | * Returns 0 if no bit is set, else returns the position of the most | |
335 | * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit). | |
f9830efd | 336 | */ |
24365af7 MD |
337 | #if defined(__i386) || defined(__x86_64) |
338 | static inline | |
339 | unsigned int fls_u32(uint32_t x) | |
f9830efd | 340 | { |
24365af7 MD |
341 | int r; |
342 | ||
343 | asm("bsrl %1,%0\n\t" | |
344 | "jnz 1f\n\t" | |
345 | "movl $-1,%0\n\t" | |
346 | "1:\n\t" | |
347 | : "=r" (r) : "rm" (x)); | |
348 | return r + 1; | |
349 | } | |
350 | #define HAS_FLS_U32 | |
351 | #endif | |
352 | ||
353 | #if defined(__x86_64) | |
354 | static inline | |
355 | unsigned int fls_u64(uint64_t x) | |
356 | { | |
357 | long r; | |
358 | ||
359 | asm("bsrq %1,%0\n\t" | |
360 | "jnz 1f\n\t" | |
361 | "movq $-1,%0\n\t" | |
362 | "1:\n\t" | |
363 | : "=r" (r) : "rm" (x)); | |
364 | return r + 1; | |
365 | } | |
366 | #define HAS_FLS_U64 | |
367 | #endif | |
368 | ||
369 | #ifndef HAS_FLS_U64 | |
370 | static __attribute__((unused)) | |
371 | unsigned int fls_u64(uint64_t x) | |
372 | { | |
373 | unsigned int r = 64; | |
374 | ||
375 | if (!x) | |
376 | return 0; | |
377 | ||
378 | if (!(x & 0xFFFFFFFF00000000ULL)) { | |
379 | x <<= 32; | |
380 | r -= 32; | |
381 | } | |
382 | if (!(x & 0xFFFF000000000000ULL)) { | |
383 | x <<= 16; | |
384 | r -= 16; | |
385 | } | |
386 | if (!(x & 0xFF00000000000000ULL)) { | |
387 | x <<= 8; | |
388 | r -= 8; | |
389 | } | |
390 | if (!(x & 0xF000000000000000ULL)) { | |
391 | x <<= 4; | |
392 | r -= 4; | |
393 | } | |
394 | if (!(x & 0xC000000000000000ULL)) { | |
395 | x <<= 2; | |
396 | r -= 2; | |
397 | } | |
398 | if (!(x & 0x8000000000000000ULL)) { | |
399 | x <<= 1; | |
400 | r -= 1; | |
401 | } | |
402 | return r; | |
403 | } | |
404 | #endif | |
405 | ||
406 | #ifndef HAS_FLS_U32 | |
407 | static __attribute__((unused)) | |
408 | unsigned int fls_u32(uint32_t x) | |
409 | { | |
410 | unsigned int r = 32; | |
f9830efd | 411 | |
24365af7 MD |
412 | if (!x) |
413 | return 0; | |
414 | if (!(x & 0xFFFF0000U)) { | |
415 | x <<= 16; | |
416 | r -= 16; | |
417 | } | |
418 | if (!(x & 0xFF000000U)) { | |
419 | x <<= 8; | |
420 | r -= 8; | |
421 | } | |
422 | if (!(x & 0xF0000000U)) { | |
423 | x <<= 4; | |
424 | r -= 4; | |
425 | } | |
426 | if (!(x & 0xC0000000U)) { | |
427 | x <<= 2; | |
428 | r -= 2; | |
429 | } | |
430 | if (!(x & 0x80000000U)) { | |
431 | x <<= 1; | |
432 | r -= 1; | |
433 | } | |
434 | return r; | |
435 | } | |
436 | #endif | |
437 | ||
5bc6b66f | 438 | unsigned int cds_lfht_fls_ulong(unsigned long x) |
f9830efd | 439 | { |
6887cc5e | 440 | #if (CAA_BITS_PER_LONG == 32) |
24365af7 MD |
441 | return fls_u32(x); |
442 | #else | |
443 | return fls_u64(x); | |
444 | #endif | |
445 | } | |
f9830efd | 446 | |
920f8ef6 LJ |
447 | /* |
448 | * Return the minimum order for which x <= (1UL << order). | |
449 | * Return -1 if x is 0. | |
450 | */ | |
5bc6b66f | 451 | int cds_lfht_get_count_order_u32(uint32_t x) |
24365af7 | 452 | { |
920f8ef6 LJ |
453 | if (!x) |
454 | return -1; | |
24365af7 | 455 | |
920f8ef6 | 456 | return fls_u32(x - 1); |
24365af7 MD |
457 | } |
458 | ||
920f8ef6 LJ |
459 | /* |
460 | * Return the minimum order for which x <= (1UL << order). | |
461 | * Return -1 if x is 0. | |
462 | */ | |
5bc6b66f | 463 | int cds_lfht_get_count_order_ulong(unsigned long x) |
24365af7 | 464 | { |
920f8ef6 LJ |
465 | if (!x) |
466 | return -1; | |
24365af7 | 467 | |
5bc6b66f | 468 | return cds_lfht_fls_ulong(x - 1); |
f9830efd MD |
469 | } |
470 | ||
471 | static | |
ab65b890 | 472 | void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth); |
f9830efd | 473 | |
f8994aee | 474 | static |
4105056a | 475 | void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, |
f8994aee MD |
476 | unsigned long count); |
477 | ||
df44348d | 478 | static long nr_cpus_mask = -1; |
4c42f1b8 LJ |
479 | static long split_count_mask = -1; |
480 | ||
4ddbb355 | 481 | #if defined(HAVE_SYSCONF) |
4c42f1b8 LJ |
482 | static void ht_init_nr_cpus_mask(void) |
483 | { | |
484 | long maxcpus; | |
485 | ||
486 | maxcpus = sysconf(_SC_NPROCESSORS_CONF); | |
487 | if (maxcpus <= 0) { | |
488 | nr_cpus_mask = -2; | |
489 | return; | |
490 | } | |
491 | /* | |
492 | * round up number of CPUs to next power of two, so we | |
493 | * can use & for modulo. | |
494 | */ | |
5bc6b66f | 495 | maxcpus = 1UL << cds_lfht_get_count_order_ulong(maxcpus); |
4c42f1b8 LJ |
496 | nr_cpus_mask = maxcpus - 1; |
497 | } | |
4ddbb355 LJ |
498 | #else /* #if defined(HAVE_SYSCONF) */ |
499 | static void ht_init_nr_cpus_mask(void) | |
500 | { | |
501 | nr_cpus_mask = -2; | |
502 | } | |
503 | #endif /* #else #if defined(HAVE_SYSCONF) */ | |
df44348d MD |
504 | |
505 | static | |
5afadd12 | 506 | void alloc_split_items_count(struct cds_lfht *ht) |
df44348d MD |
507 | { |
508 | struct ht_items_count *count; | |
509 | ||
4c42f1b8 LJ |
510 | if (nr_cpus_mask == -1) { |
511 | ht_init_nr_cpus_mask(); | |
4ddbb355 LJ |
512 | if (nr_cpus_mask < 0) |
513 | split_count_mask = DEFAULT_SPLIT_COUNT_MASK; | |
514 | else | |
515 | split_count_mask = nr_cpus_mask; | |
df44348d | 516 | } |
4c42f1b8 | 517 | |
4ddbb355 | 518 | assert(split_count_mask >= 0); |
5afadd12 LJ |
519 | |
520 | if (ht->flags & CDS_LFHT_ACCOUNTING) { | |
521 | ht->split_count = calloc(split_count_mask + 1, sizeof(*count)); | |
522 | assert(ht->split_count); | |
523 | } else { | |
524 | ht->split_count = NULL; | |
525 | } | |
df44348d MD |
526 | } |
527 | ||
528 | static | |
5afadd12 | 529 | void free_split_items_count(struct cds_lfht *ht) |
df44348d | 530 | { |
5afadd12 | 531 | poison_free(ht->split_count); |
df44348d MD |
532 | } |
533 | ||
14360f1c | 534 | #if defined(HAVE_SCHED_GETCPU) |
df44348d | 535 | static |
14360f1c | 536 | int ht_get_split_count_index(unsigned long hash) |
df44348d MD |
537 | { |
538 | int cpu; | |
539 | ||
4c42f1b8 | 540 | assert(split_count_mask >= 0); |
df44348d | 541 | cpu = sched_getcpu(); |
8ed51e04 | 542 | if (caa_unlikely(cpu < 0)) |
14360f1c | 543 | return hash & split_count_mask; |
df44348d | 544 | else |
4c42f1b8 | 545 | return cpu & split_count_mask; |
df44348d | 546 | } |
14360f1c LJ |
547 | #else /* #if defined(HAVE_SCHED_GETCPU) */ |
548 | static | |
549 | int ht_get_split_count_index(unsigned long hash) | |
550 | { | |
551 | return hash & split_count_mask; | |
552 | } | |
553 | #endif /* #else #if defined(HAVE_SCHED_GETCPU) */ | |
df44348d MD |
554 | |
555 | static | |
14360f1c | 556 | void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash) |
df44348d | 557 | { |
4c42f1b8 LJ |
558 | unsigned long split_count; |
559 | int index; | |
314558bf | 560 | long count; |
df44348d | 561 | |
8ed51e04 | 562 | if (caa_unlikely(!ht->split_count)) |
3171717f | 563 | return; |
14360f1c | 564 | index = ht_get_split_count_index(hash); |
4c42f1b8 | 565 | split_count = uatomic_add_return(&ht->split_count[index].add, 1); |
314558bf MD |
566 | if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1))) |
567 | return; | |
568 | /* Only if number of add multiple of 1UL << COUNT_COMMIT_ORDER */ | |
569 | ||
570 | dbg_printf("add split count %lu\n", split_count); | |
571 | count = uatomic_add_return(&ht->count, | |
572 | 1UL << COUNT_COMMIT_ORDER); | |
4c299dcb | 573 | if (caa_likely(count & (count - 1))) |
314558bf MD |
574 | return; |
575 | /* Only if global count is power of 2 */ | |
576 | ||
577 | if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size) | |
578 | return; | |
579 | dbg_printf("add set global %ld\n", count); | |
580 | cds_lfht_resize_lazy_count(ht, size, | |
581 | count >> (CHAIN_LEN_TARGET - 1)); | |
df44348d MD |
582 | } |
583 | ||
584 | static | |
14360f1c | 585 | void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash) |
df44348d | 586 | { |
4c42f1b8 LJ |
587 | unsigned long split_count; |
588 | int index; | |
314558bf | 589 | long count; |
df44348d | 590 | |
8ed51e04 | 591 | if (caa_unlikely(!ht->split_count)) |
3171717f | 592 | return; |
14360f1c | 593 | index = ht_get_split_count_index(hash); |
4c42f1b8 | 594 | split_count = uatomic_add_return(&ht->split_count[index].del, 1); |
314558bf MD |
595 | if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1))) |
596 | return; | |
597 | /* Only if number of deletes multiple of 1UL << COUNT_COMMIT_ORDER */ | |
598 | ||
599 | dbg_printf("del split count %lu\n", split_count); | |
600 | count = uatomic_add_return(&ht->count, | |
601 | -(1UL << COUNT_COMMIT_ORDER)); | |
4c299dcb | 602 | if (caa_likely(count & (count - 1))) |
314558bf MD |
603 | return; |
604 | /* Only if global count is power of 2 */ | |
605 | ||
606 | if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size) | |
607 | return; | |
608 | dbg_printf("del set global %ld\n", count); | |
609 | /* | |
610 | * Don't shrink table if the number of nodes is below a | |
611 | * certain threshold. | |
612 | */ | |
613 | if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1)) | |
614 | return; | |
615 | cds_lfht_resize_lazy_count(ht, size, | |
616 | count >> (CHAIN_LEN_TARGET - 1)); | |
df44348d MD |
617 | } |
618 | ||
f9830efd | 619 | static |
4105056a | 620 | void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len) |
f9830efd | 621 | { |
f8994aee MD |
622 | unsigned long count; |
623 | ||
b8af5011 MD |
624 | if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) |
625 | return; | |
f8994aee MD |
626 | count = uatomic_read(&ht->count); |
627 | /* | |
628 | * Use bucket-local length for small table expand and for | |
629 | * environments lacking per-cpu data support. | |
630 | */ | |
631 | if (count >= (1UL << COUNT_COMMIT_ORDER)) | |
632 | return; | |
24365af7 | 633 | if (chain_len > 100) |
f0c29ed7 | 634 | dbg_printf("WARNING: large chain length: %u.\n", |
24365af7 | 635 | chain_len); |
3390d470 | 636 | if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) |
ab65b890 | 637 | cds_lfht_resize_lazy_grow(ht, size, |
5bc6b66f | 638 | cds_lfht_get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1))); |
f9830efd MD |
639 | } |
640 | ||
abc490a1 | 641 | static |
14044b37 | 642 | struct cds_lfht_node *clear_flag(struct cds_lfht_node *node) |
abc490a1 | 643 | { |
14044b37 | 644 | return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK); |
abc490a1 MD |
645 | } |
646 | ||
647 | static | |
14044b37 | 648 | int is_removed(struct cds_lfht_node *node) |
abc490a1 | 649 | { |
d37166c6 | 650 | return ((unsigned long) node) & REMOVED_FLAG; |
abc490a1 MD |
651 | } |
652 | ||
653 | static | |
14044b37 | 654 | struct cds_lfht_node *flag_removed(struct cds_lfht_node *node) |
abc490a1 | 655 | { |
14044b37 | 656 | return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG); |
abc490a1 MD |
657 | } |
658 | ||
f5596c94 | 659 | static |
1ee8f000 | 660 | int is_bucket(struct cds_lfht_node *node) |
f5596c94 | 661 | { |
1ee8f000 | 662 | return ((unsigned long) node) & BUCKET_FLAG; |
f5596c94 MD |
663 | } |
664 | ||
665 | static | |
1ee8f000 | 666 | struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node) |
f5596c94 | 667 | { |
1ee8f000 | 668 | return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG); |
f5596c94 | 669 | } |
bb7b2f26 | 670 | |
db00ccc3 MD |
671 | static |
672 | int is_removal_owner(struct cds_lfht_node *node) | |
673 | { | |
674 | return ((unsigned long) node) & REMOVAL_OWNER_FLAG; | |
675 | } | |
676 | ||
677 | static | |
678 | struct cds_lfht_node *flag_removal_owner(struct cds_lfht_node *node) | |
679 | { | |
680 | return (struct cds_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG); | |
681 | } | |
682 | ||
bb7b2f26 MD |
683 | static |
684 | struct cds_lfht_node *get_end(void) | |
685 | { | |
686 | return (struct cds_lfht_node *) END_VALUE; | |
687 | } | |
688 | ||
689 | static | |
690 | int is_end(struct cds_lfht_node *node) | |
691 | { | |
692 | return clear_flag(node) == (struct cds_lfht_node *) END_VALUE; | |
693 | } | |
694 | ||
abc490a1 | 695 | static |
ab65b890 LJ |
696 | unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr, |
697 | unsigned long v) | |
abc490a1 MD |
698 | { |
699 | unsigned long old1, old2; | |
700 | ||
701 | old1 = uatomic_read(ptr); | |
702 | do { | |
703 | old2 = old1; | |
704 | if (old2 >= v) | |
f9830efd | 705 | return old2; |
abc490a1 | 706 | } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); |
ab65b890 | 707 | return old2; |
abc490a1 MD |
708 | } |
709 | ||
48f1b16d LJ |
710 | static |
711 | void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order) | |
712 | { | |
0b6aa001 | 713 | return ht->mm->alloc_bucket_table(ht, order); |
48f1b16d LJ |
714 | } |
715 | ||
716 | /* | |
717 | * cds_lfht_free_bucket_table() should be called with decreasing order. | |
718 | * When cds_lfht_free_bucket_table(0) is called, it means the whole | |
719 | * lfht is destroyed. | |
720 | */ | |
721 | static | |
722 | void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order) | |
723 | { | |
0b6aa001 | 724 | return ht->mm->free_bucket_table(ht, order); |
48f1b16d LJ |
725 | } |
726 | ||
9d72a73f LJ |
727 | static inline |
728 | struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index) | |
f4a9cc0b | 729 | { |
0b6aa001 | 730 | return ht->bucket_at(ht, index); |
f4a9cc0b LJ |
731 | } |
732 | ||
9d72a73f LJ |
733 | static inline |
734 | struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size, | |
735 | unsigned long hash) | |
736 | { | |
737 | assert(size > 0); | |
738 | return bucket_at(ht, hash & (size - 1)); | |
739 | } | |
740 | ||
273399de MD |
741 | /* |
742 | * Remove all logically deleted nodes from a bucket up to a certain node key. | |
743 | */ | |
744 | static | |
1ee8f000 | 745 | void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node) |
273399de | 746 | { |
14044b37 | 747 | struct cds_lfht_node *iter_prev, *iter, *next, *new_next; |
273399de | 748 | |
1ee8f000 LJ |
749 | assert(!is_bucket(bucket)); |
750 | assert(!is_removed(bucket)); | |
751 | assert(!is_bucket(node)); | |
c90201ac | 752 | assert(!is_removed(node)); |
273399de | 753 | for (;;) { |
1ee8f000 LJ |
754 | iter_prev = bucket; |
755 | /* We can always skip the bucket node initially */ | |
04db56f8 | 756 | iter = rcu_dereference(iter_prev->next); |
b4cb483f | 757 | assert(!is_removed(iter)); |
04db56f8 | 758 | assert(iter_prev->reverse_hash <= node->reverse_hash); |
bd4db153 | 759 | /* |
1ee8f000 | 760 | * We should never be called with bucket (start of chain) |
bd4db153 MD |
761 | * and logically removed node (end of path compression |
762 | * marker) being the actual same node. This would be a | |
763 | * bug in the algorithm implementation. | |
764 | */ | |
1ee8f000 | 765 | assert(bucket != node); |
273399de | 766 | for (;;) { |
8ed51e04 | 767 | if (caa_unlikely(is_end(iter))) |
f9c80341 | 768 | return; |
04db56f8 | 769 | if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash)) |
f9c80341 | 770 | return; |
04db56f8 | 771 | next = rcu_dereference(clear_flag(iter)->next); |
8ed51e04 | 772 | if (caa_likely(is_removed(next))) |
273399de | 773 | break; |
b453eae1 | 774 | iter_prev = clear_flag(iter); |
273399de MD |
775 | iter = next; |
776 | } | |
b198f0fd | 777 | assert(!is_removed(iter)); |
1ee8f000 LJ |
778 | if (is_bucket(iter)) |
779 | new_next = flag_bucket(clear_flag(next)); | |
f5596c94 MD |
780 | else |
781 | new_next = clear_flag(next); | |
04db56f8 | 782 | (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next); |
273399de MD |
783 | } |
784 | } | |
785 | ||
9357c415 MD |
786 | static |
787 | int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size, | |
788 | struct cds_lfht_node *old_node, | |
3fb86f26 | 789 | struct cds_lfht_node *old_next, |
9357c415 MD |
790 | struct cds_lfht_node *new_node) |
791 | { | |
04db56f8 | 792 | struct cds_lfht_node *bucket, *ret_next; |
9357c415 MD |
793 | |
794 | if (!old_node) /* Return -ENOENT if asked to replace NULL node */ | |
7801dadd | 795 | return -ENOENT; |
9357c415 MD |
796 | |
797 | assert(!is_removed(old_node)); | |
1ee8f000 | 798 | assert(!is_bucket(old_node)); |
9357c415 | 799 | assert(!is_removed(new_node)); |
1ee8f000 | 800 | assert(!is_bucket(new_node)); |
9357c415 | 801 | assert(new_node != old_node); |
3fb86f26 | 802 | for (;;) { |
9357c415 | 803 | /* Insert after node to be replaced */ |
9357c415 MD |
804 | if (is_removed(old_next)) { |
805 | /* | |
806 | * Too late, the old node has been removed under us | |
807 | * between lookup and replace. Fail. | |
808 | */ | |
7801dadd | 809 | return -ENOENT; |
9357c415 | 810 | } |
feda2722 LJ |
811 | assert(old_next == clear_flag(old_next)); |
812 | assert(new_node != old_next); | |
813 | new_node->next = old_next; | |
9357c415 MD |
814 | /* |
815 | * Here is the whole trick for lock-free replace: we add | |
816 | * the replacement node _after_ the node we want to | |
817 | * replace by atomically setting its next pointer at the | |
818 | * same time we set its removal flag. Given that | |
819 | * the lookups/get next use an iterator aware of the | |
820 | * next pointer, they will either skip the old node due | |
821 | * to the removal flag and see the new node, or use | |
822 | * the old node, but will not see the new one. | |
db00ccc3 MD |
823 | * This is a replacement of a node with another node |
824 | * that has the same value: we are therefore not | |
825 | * removing a value from the hash table. | |
9357c415 | 826 | */ |
04db56f8 | 827 | ret_next = uatomic_cmpxchg(&old_node->next, |
9357c415 | 828 | old_next, flag_removed(new_node)); |
3fb86f26 | 829 | if (ret_next == old_next) |
7801dadd | 830 | break; /* We performed the replacement. */ |
3fb86f26 LJ |
831 | old_next = ret_next; |
832 | } | |
9357c415 | 833 | |
9357c415 MD |
834 | /* |
835 | * Ensure that the old node is not visible to readers anymore: | |
836 | * lookup for the node, and remove it (along with any other | |
837 | * logically removed node) if found. | |
838 | */ | |
04db56f8 LJ |
839 | bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash)); |
840 | _cds_lfht_gc_bucket(bucket, new_node); | |
7801dadd | 841 | |
04db56f8 | 842 | assert(is_removed(rcu_dereference(old_node->next))); |
7801dadd | 843 | return 0; |
9357c415 MD |
844 | } |
845 | ||
83beee94 MD |
846 | /* |
847 | * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add | |
848 | * mode. A NULL unique_ret allows creation of duplicate keys. | |
849 | */ | |
abc490a1 | 850 | static |
83beee94 | 851 | void _cds_lfht_add(struct cds_lfht *ht, |
91a75cc5 | 852 | unsigned long hash, |
0422d92c | 853 | cds_lfht_match_fct match, |
996ff57c | 854 | const void *key, |
83beee94 MD |
855 | unsigned long size, |
856 | struct cds_lfht_node *node, | |
857 | struct cds_lfht_iter *unique_ret, | |
1ee8f000 | 858 | int bucket_flag) |
abc490a1 | 859 | { |
14044b37 | 860 | struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next, |
960c9e4f | 861 | *return_node; |
04db56f8 | 862 | struct cds_lfht_node *bucket; |
abc490a1 | 863 | |
1ee8f000 | 864 | assert(!is_bucket(node)); |
c90201ac | 865 | assert(!is_removed(node)); |
91a75cc5 | 866 | bucket = lookup_bucket(ht, size, hash); |
abc490a1 | 867 | for (;;) { |
adc0de68 | 868 | uint32_t chain_len = 0; |
abc490a1 | 869 | |
11519af6 MD |
870 | /* |
871 | * iter_prev points to the non-removed node prior to the | |
872 | * insert location. | |
11519af6 | 873 | */ |
04db56f8 | 874 | iter_prev = bucket; |
1ee8f000 | 875 | /* We can always skip the bucket node initially */ |
04db56f8 LJ |
876 | iter = rcu_dereference(iter_prev->next); |
877 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
abc490a1 | 878 | for (;;) { |
8ed51e04 | 879 | if (caa_unlikely(is_end(iter))) |
273399de | 880 | goto insert; |
04db56f8 | 881 | if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash)) |
273399de | 882 | goto insert; |
238cc06e | 883 | |
1ee8f000 LJ |
884 | /* bucket node is the first node of the identical-hash-value chain */ |
885 | if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash) | |
194fdbd1 | 886 | goto insert; |
238cc06e | 887 | |
04db56f8 | 888 | next = rcu_dereference(clear_flag(iter)->next); |
8ed51e04 | 889 | if (caa_unlikely(is_removed(next))) |
9dba85be | 890 | goto gc_node; |
238cc06e LJ |
891 | |
892 | /* uniquely add */ | |
83beee94 | 893 | if (unique_ret |
1ee8f000 | 894 | && !is_bucket(next) |
04db56f8 | 895 | && clear_flag(iter)->reverse_hash == node->reverse_hash) { |
238cc06e LJ |
896 | struct cds_lfht_iter d_iter = { .node = node, .next = iter, }; |
897 | ||
898 | /* | |
899 | * uniquely adding inserts the node as the first | |
900 | * node of the identical-hash-value node chain. | |
901 | * | |
902 | * This semantic ensures no duplicated keys | |
903 | * should ever be observable in the table | |
904 | * (including observe one node by one node | |
905 | * by forward iterations) | |
906 | */ | |
04db56f8 | 907 | cds_lfht_next_duplicate(ht, match, key, &d_iter); |
238cc06e LJ |
908 | if (!d_iter.node) |
909 | goto insert; | |
910 | ||
911 | *unique_ret = d_iter; | |
83beee94 | 912 | return; |
48ed1c18 | 913 | } |
238cc06e | 914 | |
11519af6 | 915 | /* Only account for identical reverse hash once */ |
04db56f8 | 916 | if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash |
1ee8f000 | 917 | && !is_bucket(next)) |
4105056a | 918 | check_resize(ht, size, ++chain_len); |
11519af6 | 919 | iter_prev = clear_flag(iter); |
273399de | 920 | iter = next; |
abc490a1 | 921 | } |
48ed1c18 | 922 | |
273399de | 923 | insert: |
7ec59d3b | 924 | assert(node != clear_flag(iter)); |
11519af6 | 925 | assert(!is_removed(iter_prev)); |
c90201ac | 926 | assert(!is_removed(iter)); |
f000907d | 927 | assert(iter_prev != node); |
1ee8f000 | 928 | if (!bucket_flag) |
04db56f8 | 929 | node->next = clear_flag(iter); |
f9c80341 | 930 | else |
1ee8f000 LJ |
931 | node->next = flag_bucket(clear_flag(iter)); |
932 | if (is_bucket(iter)) | |
933 | new_node = flag_bucket(node); | |
f5596c94 MD |
934 | else |
935 | new_node = node; | |
04db56f8 | 936 | if (uatomic_cmpxchg(&iter_prev->next, iter, |
48ed1c18 | 937 | new_node) != iter) { |
273399de | 938 | continue; /* retry */ |
48ed1c18 | 939 | } else { |
83beee94 | 940 | return_node = node; |
960c9e4f | 941 | goto end; |
48ed1c18 MD |
942 | } |
943 | ||
9dba85be MD |
944 | gc_node: |
945 | assert(!is_removed(iter)); | |
1ee8f000 LJ |
946 | if (is_bucket(iter)) |
947 | new_next = flag_bucket(clear_flag(next)); | |
f5596c94 MD |
948 | else |
949 | new_next = clear_flag(next); | |
04db56f8 | 950 | (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next); |
273399de | 951 | /* retry */ |
464a1ec9 | 952 | } |
9357c415 | 953 | end: |
83beee94 MD |
954 | if (unique_ret) { |
955 | unique_ret->node = return_node; | |
956 | /* unique_ret->next left unset, never used. */ | |
957 | } | |
abc490a1 | 958 | } |
464a1ec9 | 959 | |
abc490a1 | 960 | static |
860d07e8 | 961 | int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, |
b65ec430 | 962 | struct cds_lfht_node *node) |
abc490a1 | 963 | { |
db00ccc3 | 964 | struct cds_lfht_node *bucket, *next; |
5e28c532 | 965 | |
9357c415 | 966 | if (!node) /* Return -ENOENT if asked to delete NULL node */ |
743f9143 | 967 | return -ENOENT; |
9357c415 | 968 | |
7ec59d3b | 969 | /* logically delete the node */ |
1ee8f000 | 970 | assert(!is_bucket(node)); |
c90201ac | 971 | assert(!is_removed(node)); |
db00ccc3 | 972 | assert(!is_removal_owner(node)); |
48ed1c18 | 973 | |
db00ccc3 MD |
974 | /* |
975 | * We are first checking if the node had previously been | |
976 | * logically removed (this check is not atomic with setting the | |
977 | * logical removal flag). Return -ENOENT if the node had | |
978 | * previously been removed. | |
979 | */ | |
980 | next = rcu_dereference(node->next); | |
981 | if (caa_unlikely(is_removed(next))) | |
982 | return -ENOENT; | |
b65ec430 | 983 | assert(!is_bucket(next)); |
db00ccc3 MD |
984 | /* |
985 | * We set the REMOVED_FLAG unconditionally. Note that there may | |
986 | * be more than one concurrent thread setting this flag. | |
987 | * Knowing which wins the race will be known after the garbage | |
988 | * collection phase, stay tuned! | |
989 | */ | |
990 | uatomic_or(&node->next, REMOVED_FLAG); | |
7ec59d3b | 991 | /* We performed the (logical) deletion. */ |
7ec59d3b MD |
992 | |
993 | /* | |
994 | * Ensure that the node is not visible to readers anymore: lookup for | |
273399de MD |
995 | * the node, and remove it (along with any other logically removed node) |
996 | * if found. | |
11519af6 | 997 | */ |
04db56f8 LJ |
998 | bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash)); |
999 | _cds_lfht_gc_bucket(bucket, node); | |
743f9143 | 1000 | |
04db56f8 | 1001 | assert(is_removed(rcu_dereference(node->next))); |
db00ccc3 MD |
1002 | /* |
1003 | * Last phase: atomically exchange node->next with a version | |
1004 | * having "REMOVAL_OWNER_FLAG" set. If the returned node->next | |
1005 | * pointer did _not_ have "REMOVAL_OWNER_FLAG" set, we now own | |
1006 | * the node and win the removal race. | |
1007 | * It is interesting to note that all "add" paths are forbidden | |
1008 | * to change the next pointer starting from the point where the | |
1009 | * REMOVED_FLAG is set, so here using a read, followed by a | |
1010 | * xchg() suffice to guarantee that the xchg() will ever only | |
1011 | * set the "REMOVAL_OWNER_FLAG" (or change nothing if the flag | |
1012 | * was already set). | |
1013 | */ | |
1014 | if (!is_removal_owner(uatomic_xchg(&node->next, | |
1015 | flag_removal_owner(node->next)))) | |
1016 | return 0; | |
1017 | else | |
1018 | return -ENOENT; | |
abc490a1 | 1019 | } |
2ed95849 | 1020 | |
b7d619b0 MD |
1021 | static |
1022 | void *partition_resize_thread(void *arg) | |
1023 | { | |
1024 | struct partition_resize_work *work = arg; | |
1025 | ||
7b17c13e | 1026 | work->ht->flavor->register_thread(); |
b7d619b0 | 1027 | work->fct(work->ht, work->i, work->start, work->len); |
7b17c13e | 1028 | work->ht->flavor->unregister_thread(); |
b7d619b0 MD |
1029 | return NULL; |
1030 | } | |
1031 | ||
1032 | static | |
1033 | void partition_resize_helper(struct cds_lfht *ht, unsigned long i, | |
1034 | unsigned long len, | |
1035 | void (*fct)(struct cds_lfht *ht, unsigned long i, | |
1036 | unsigned long start, unsigned long len)) | |
1037 | { | |
1038 | unsigned long partition_len; | |
1039 | struct partition_resize_work *work; | |
6083a889 MD |
1040 | int thread, ret; |
1041 | unsigned long nr_threads; | |
b7d619b0 | 1042 | |
6083a889 MD |
1043 | /* |
1044 | * Note: nr_cpus_mask + 1 is always power of 2. | |
1045 | * We spawn just the number of threads we need to satisfy the minimum | |
1046 | * partition size, up to the number of CPUs in the system. | |
1047 | */ | |
91452a6a MD |
1048 | if (nr_cpus_mask > 0) { |
1049 | nr_threads = min(nr_cpus_mask + 1, | |
1050 | len >> MIN_PARTITION_PER_THREAD_ORDER); | |
1051 | } else { | |
1052 | nr_threads = 1; | |
1053 | } | |
5bc6b66f | 1054 | partition_len = len >> cds_lfht_get_count_order_ulong(nr_threads); |
6083a889 | 1055 | work = calloc(nr_threads, sizeof(*work)); |
b7d619b0 | 1056 | assert(work); |
6083a889 MD |
1057 | for (thread = 0; thread < nr_threads; thread++) { |
1058 | work[thread].ht = ht; | |
1059 | work[thread].i = i; | |
1060 | work[thread].len = partition_len; | |
1061 | work[thread].start = thread * partition_len; | |
1062 | work[thread].fct = fct; | |
1af6e26e | 1063 | ret = pthread_create(&(work[thread].thread_id), ht->resize_attr, |
6083a889 | 1064 | partition_resize_thread, &work[thread]); |
b7d619b0 MD |
1065 | assert(!ret); |
1066 | } | |
6083a889 | 1067 | for (thread = 0; thread < nr_threads; thread++) { |
1af6e26e | 1068 | ret = pthread_join(work[thread].thread_id, NULL); |
b7d619b0 MD |
1069 | assert(!ret); |
1070 | } | |
1071 | free(work); | |
b7d619b0 MD |
1072 | } |
1073 | ||
e8de508e MD |
1074 | /* |
1075 | * Holding RCU read lock to protect _cds_lfht_add against memory | |
1076 | * reclaim that could be performed by other call_rcu worker threads (ABA | |
1077 | * problem). | |
9ee0fc9a | 1078 | * |
b7d619b0 | 1079 | * When we reach a certain length, we can split this population phase over |
9ee0fc9a MD |
1080 | * many worker threads, based on the number of CPUs available in the system. |
1081 | * This should therefore take care of not having the expand lagging behind too | |
1082 | * many concurrent insertion threads by using the scheduler's ability to | |
1ee8f000 | 1083 | * schedule bucket node population fairly with insertions. |
e8de508e | 1084 | */ |
4105056a | 1085 | static |
b7d619b0 MD |
1086 | void init_table_populate_partition(struct cds_lfht *ht, unsigned long i, |
1087 | unsigned long start, unsigned long len) | |
4105056a | 1088 | { |
9d72a73f | 1089 | unsigned long j, size = 1UL << (i - 1); |
4105056a | 1090 | |
d0d8f9aa | 1091 | assert(i > MIN_TABLE_ORDER); |
7b17c13e | 1092 | ht->flavor->read_lock(); |
9d72a73f LJ |
1093 | for (j = size + start; j < size + start + len; j++) { |
1094 | struct cds_lfht_node *new_node = bucket_at(ht, j); | |
1095 | ||
1096 | assert(j >= size && j < (size << 1)); | |
1097 | dbg_printf("init populate: order %lu index %lu hash %lu\n", | |
1098 | i, j, j); | |
1099 | new_node->reverse_hash = bit_reverse_ulong(j); | |
91a75cc5 | 1100 | _cds_lfht_add(ht, j, NULL, NULL, size, new_node, NULL, 1); |
4105056a | 1101 | } |
7b17c13e | 1102 | ht->flavor->read_unlock(); |
b7d619b0 MD |
1103 | } |
1104 | ||
1105 | static | |
1106 | void init_table_populate(struct cds_lfht *ht, unsigned long i, | |
1107 | unsigned long len) | |
1108 | { | |
1109 | assert(nr_cpus_mask != -1); | |
6083a889 | 1110 | if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { |
7b17c13e | 1111 | ht->flavor->thread_online(); |
b7d619b0 | 1112 | init_table_populate_partition(ht, i, 0, len); |
7b17c13e | 1113 | ht->flavor->thread_offline(); |
b7d619b0 MD |
1114 | return; |
1115 | } | |
1116 | partition_resize_helper(ht, i, len, init_table_populate_partition); | |
4105056a MD |
1117 | } |
1118 | ||
abc490a1 | 1119 | static |
4105056a | 1120 | void init_table(struct cds_lfht *ht, |
93d46c39 | 1121 | unsigned long first_order, unsigned long last_order) |
24365af7 | 1122 | { |
93d46c39 | 1123 | unsigned long i; |
24365af7 | 1124 | |
93d46c39 LJ |
1125 | dbg_printf("init table: first_order %lu last_order %lu\n", |
1126 | first_order, last_order); | |
d0d8f9aa | 1127 | assert(first_order > MIN_TABLE_ORDER); |
93d46c39 | 1128 | for (i = first_order; i <= last_order; i++) { |
4105056a | 1129 | unsigned long len; |
24365af7 | 1130 | |
4f6e90b7 | 1131 | len = 1UL << (i - 1); |
f0c29ed7 | 1132 | dbg_printf("init order %lu len: %lu\n", i, len); |
4d676753 MD |
1133 | |
1134 | /* Stop expand if the resize target changes under us */ | |
7b3893e4 | 1135 | if (CMM_LOAD_SHARED(ht->resize_target) < (1UL << i)) |
4d676753 MD |
1136 | break; |
1137 | ||
48f1b16d | 1138 | cds_lfht_alloc_bucket_table(ht, i); |
4105056a | 1139 | |
4105056a | 1140 | /* |
1ee8f000 LJ |
1141 | * Set all bucket nodes reverse hash values for a level and |
1142 | * link all bucket nodes into the table. | |
4105056a | 1143 | */ |
dc1da8f6 | 1144 | init_table_populate(ht, i, len); |
4105056a | 1145 | |
f9c80341 MD |
1146 | /* |
1147 | * Update table size. | |
1148 | */ | |
1149 | cmm_smp_wmb(); /* populate data before RCU size */ | |
7b3893e4 | 1150 | CMM_STORE_SHARED(ht->size, 1UL << i); |
f9c80341 | 1151 | |
4f6e90b7 | 1152 | dbg_printf("init new size: %lu\n", 1UL << i); |
4105056a MD |
1153 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
1154 | break; | |
1155 | } | |
1156 | } | |
1157 | ||
e8de508e MD |
1158 | /* |
1159 | * Holding RCU read lock to protect _cds_lfht_remove against memory | |
1160 | * reclaim that could be performed by other call_rcu worker threads (ABA | |
1161 | * problem). | |
1162 | * For a single level, we logically remove and garbage collect each node. | |
1163 | * | |
1164 | * As a design choice, we perform logical removal and garbage collection on a | |
1165 | * node-per-node basis to simplify this algorithm. We also assume keeping good | |
1166 | * cache locality of the operation would overweight possible performance gain | |
1167 | * that could be achieved by batching garbage collection for multiple levels. | |
1168 | * However, this would have to be justified by benchmarks. | |
1169 | * | |
1170 | * Concurrent removal and add operations are helping us perform garbage | |
1171 | * collection of logically removed nodes. We guarantee that all logically | |
1172 | * removed nodes have been garbage-collected (unlinked) before call_rcu is | |
1ee8f000 | 1173 | * invoked to free a hole level of bucket nodes (after a grace period). |
e8de508e MD |
1174 | * |
1175 | * Logical removal and garbage collection can therefore be done in batch or on a | |
1176 | * node-per-node basis, as long as the guarantee above holds. | |
9ee0fc9a | 1177 | * |
b7d619b0 MD |
1178 | * When we reach a certain length, we can split this removal over many worker |
1179 | * threads, based on the number of CPUs available in the system. This should | |
1180 | * take care of not letting resize process lag behind too many concurrent | |
9ee0fc9a | 1181 | * updater threads actively inserting into the hash table. |
e8de508e | 1182 | */ |
4105056a | 1183 | static |
b7d619b0 MD |
1184 | void remove_table_partition(struct cds_lfht *ht, unsigned long i, |
1185 | unsigned long start, unsigned long len) | |
4105056a | 1186 | { |
9d72a73f | 1187 | unsigned long j, size = 1UL << (i - 1); |
4105056a | 1188 | |
d0d8f9aa | 1189 | assert(i > MIN_TABLE_ORDER); |
7b17c13e | 1190 | ht->flavor->read_lock(); |
9d72a73f | 1191 | for (j = size + start; j < size + start + len; j++) { |
2e2ce1e9 LJ |
1192 | struct cds_lfht_node *fini_bucket = bucket_at(ht, j); |
1193 | struct cds_lfht_node *parent_bucket = bucket_at(ht, j - size); | |
9d72a73f LJ |
1194 | |
1195 | assert(j >= size && j < (size << 1)); | |
1196 | dbg_printf("remove entry: order %lu index %lu hash %lu\n", | |
1197 | i, j, j); | |
2e2ce1e9 LJ |
1198 | /* Set the REMOVED_FLAG to freeze the ->next for gc */ |
1199 | uatomic_or(&fini_bucket->next, REMOVED_FLAG); | |
1200 | _cds_lfht_gc_bucket(parent_bucket, fini_bucket); | |
abc490a1 | 1201 | } |
7b17c13e | 1202 | ht->flavor->read_unlock(); |
b7d619b0 MD |
1203 | } |
1204 | ||
1205 | static | |
1206 | void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len) | |
1207 | { | |
1208 | ||
1209 | assert(nr_cpus_mask != -1); | |
6083a889 | 1210 | if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { |
7b17c13e | 1211 | ht->flavor->thread_online(); |
b7d619b0 | 1212 | remove_table_partition(ht, i, 0, len); |
7b17c13e | 1213 | ht->flavor->thread_offline(); |
b7d619b0 MD |
1214 | return; |
1215 | } | |
1216 | partition_resize_helper(ht, i, len, remove_table_partition); | |
2ed95849 MD |
1217 | } |
1218 | ||
61adb337 MD |
1219 | /* |
1220 | * fini_table() is never called for first_order == 0, which is why | |
1221 | * free_by_rcu_order == 0 can be used as criterion to know if free must | |
1222 | * be called. | |
1223 | */ | |
1475579c | 1224 | static |
4105056a | 1225 | void fini_table(struct cds_lfht *ht, |
93d46c39 | 1226 | unsigned long first_order, unsigned long last_order) |
1475579c | 1227 | { |
93d46c39 | 1228 | long i; |
48f1b16d | 1229 | unsigned long free_by_rcu_order = 0; |
1475579c | 1230 | |
93d46c39 LJ |
1231 | dbg_printf("fini table: first_order %lu last_order %lu\n", |
1232 | first_order, last_order); | |
d0d8f9aa | 1233 | assert(first_order > MIN_TABLE_ORDER); |
93d46c39 | 1234 | for (i = last_order; i >= first_order; i--) { |
4105056a | 1235 | unsigned long len; |
1475579c | 1236 | |
4f6e90b7 | 1237 | len = 1UL << (i - 1); |
1475579c | 1238 | dbg_printf("fini order %lu len: %lu\n", i, len); |
4105056a | 1239 | |
4d676753 | 1240 | /* Stop shrink if the resize target changes under us */ |
7b3893e4 | 1241 | if (CMM_LOAD_SHARED(ht->resize_target) > (1UL << (i - 1))) |
4d676753 MD |
1242 | break; |
1243 | ||
1244 | cmm_smp_wmb(); /* populate data before RCU size */ | |
7b3893e4 | 1245 | CMM_STORE_SHARED(ht->size, 1UL << (i - 1)); |
4d676753 MD |
1246 | |
1247 | /* | |
1248 | * We need to wait for all add operations to reach Q.S. (and | |
1249 | * thus use the new table for lookups) before we can start | |
1ee8f000 | 1250 | * releasing the old bucket nodes. Otherwise their lookup will |
4d676753 MD |
1251 | * return a logically removed node as insert position. |
1252 | */ | |
7b17c13e | 1253 | ht->flavor->update_synchronize_rcu(); |
48f1b16d LJ |
1254 | if (free_by_rcu_order) |
1255 | cds_lfht_free_bucket_table(ht, free_by_rcu_order); | |
4d676753 | 1256 | |
21263e21 | 1257 | /* |
1ee8f000 LJ |
1258 | * Set "removed" flag in bucket nodes about to be removed. |
1259 | * Unlink all now-logically-removed bucket node pointers. | |
4105056a MD |
1260 | * Concurrent add/remove operation are helping us doing |
1261 | * the gc. | |
21263e21 | 1262 | */ |
4105056a MD |
1263 | remove_table(ht, i, len); |
1264 | ||
48f1b16d | 1265 | free_by_rcu_order = i; |
4105056a MD |
1266 | |
1267 | dbg_printf("fini new size: %lu\n", 1UL << i); | |
1475579c MD |
1268 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
1269 | break; | |
1270 | } | |
0d14ceb2 | 1271 | |
48f1b16d | 1272 | if (free_by_rcu_order) { |
7b17c13e | 1273 | ht->flavor->update_synchronize_rcu(); |
48f1b16d | 1274 | cds_lfht_free_bucket_table(ht, free_by_rcu_order); |
0d14ceb2 | 1275 | } |
1475579c MD |
1276 | } |
1277 | ||
ff0d69de | 1278 | static |
1ee8f000 | 1279 | void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size) |
ff0d69de | 1280 | { |
04db56f8 | 1281 | struct cds_lfht_node *prev, *node; |
9d72a73f | 1282 | unsigned long order, len, i; |
ff0d69de | 1283 | |
48f1b16d | 1284 | cds_lfht_alloc_bucket_table(ht, 0); |
ff0d69de | 1285 | |
9d72a73f LJ |
1286 | dbg_printf("create bucket: order 0 index 0 hash 0\n"); |
1287 | node = bucket_at(ht, 0); | |
1288 | node->next = flag_bucket(get_end()); | |
1289 | node->reverse_hash = 0; | |
ff0d69de | 1290 | |
5bc6b66f | 1291 | for (order = 1; order < cds_lfht_get_count_order_ulong(size) + 1; order++) { |
ff0d69de | 1292 | len = 1UL << (order - 1); |
48f1b16d | 1293 | cds_lfht_alloc_bucket_table(ht, order); |
ff0d69de | 1294 | |
9d72a73f LJ |
1295 | for (i = 0; i < len; i++) { |
1296 | /* | |
1297 | * Now, we are trying to init the node with the | |
1298 | * hash=(len+i) (which is also a bucket with the | |
1299 | * index=(len+i)) and insert it into the hash table, | |
1300 | * so this node has to be inserted after the bucket | |
1301 | * with the index=(len+i)&(len-1)=i. And because there | |
1302 | * is no other non-bucket node nor bucket node with | |
1303 | * larger index/hash inserted, so the bucket node | |
1304 | * being inserted should be inserted directly linked | |
1305 | * after the bucket node with index=i. | |
1306 | */ | |
1307 | prev = bucket_at(ht, i); | |
1308 | node = bucket_at(ht, len + i); | |
ff0d69de | 1309 | |
1ee8f000 | 1310 | dbg_printf("create bucket: order %lu index %lu hash %lu\n", |
9d72a73f LJ |
1311 | order, len + i, len + i); |
1312 | node->reverse_hash = bit_reverse_ulong(len + i); | |
1313 | ||
1314 | /* insert after prev */ | |
1315 | assert(is_bucket(prev->next)); | |
ff0d69de | 1316 | node->next = prev->next; |
1ee8f000 | 1317 | prev->next = flag_bucket(node); |
ff0d69de LJ |
1318 | } |
1319 | } | |
1320 | } | |
1321 | ||
0422d92c | 1322 | struct cds_lfht *_cds_lfht_new(unsigned long init_size, |
0722081a | 1323 | unsigned long min_nr_alloc_buckets, |
747d725c | 1324 | unsigned long max_nr_buckets, |
b8af5011 | 1325 | int flags, |
0b6aa001 | 1326 | const struct cds_lfht_mm_type *mm, |
7b17c13e | 1327 | const struct rcu_flavor_struct *flavor, |
b7d619b0 | 1328 | pthread_attr_t *attr) |
abc490a1 | 1329 | { |
14044b37 | 1330 | struct cds_lfht *ht; |
24365af7 | 1331 | unsigned long order; |
abc490a1 | 1332 | |
0722081a LJ |
1333 | /* min_nr_alloc_buckets must be power of two */ |
1334 | if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1))) | |
5488222b | 1335 | return NULL; |
747d725c | 1336 | |
8129be4e | 1337 | /* init_size must be power of two */ |
5488222b | 1338 | if (!init_size || (init_size & (init_size - 1))) |
8129be4e | 1339 | return NULL; |
747d725c | 1340 | |
c1888f3a MD |
1341 | /* |
1342 | * Memory management plugin default. | |
1343 | */ | |
1344 | if (!mm) { | |
5a2141a7 MD |
1345 | if (CAA_BITS_PER_LONG > 32 |
1346 | && max_nr_buckets | |
c1888f3a MD |
1347 | && max_nr_buckets <= (1ULL << 32)) { |
1348 | /* | |
1349 | * For 64-bit architectures, with max number of | |
1350 | * buckets small enough not to use the entire | |
1351 | * 64-bit memory mapping space (and allowing a | |
1352 | * fair number of hash table instances), use the | |
1353 | * mmap allocator, which is faster than the | |
1354 | * order allocator. | |
1355 | */ | |
1356 | mm = &cds_lfht_mm_mmap; | |
1357 | } else { | |
1358 | /* | |
1359 | * The fallback is to use the order allocator. | |
1360 | */ | |
1361 | mm = &cds_lfht_mm_order; | |
1362 | } | |
1363 | } | |
1364 | ||
0b6aa001 LJ |
1365 | /* max_nr_buckets == 0 for order based mm means infinite */ |
1366 | if (mm == &cds_lfht_mm_order && !max_nr_buckets) | |
747d725c LJ |
1367 | max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1); |
1368 | ||
1369 | /* max_nr_buckets must be power of two */ | |
1370 | if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1))) | |
1371 | return NULL; | |
1372 | ||
0722081a | 1373 | min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE); |
d0d8f9aa | 1374 | init_size = max(init_size, MIN_TABLE_SIZE); |
747d725c LJ |
1375 | max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets); |
1376 | init_size = min(init_size, max_nr_buckets); | |
0b6aa001 LJ |
1377 | |
1378 | ht = mm->alloc_cds_lfht(min_nr_alloc_buckets, max_nr_buckets); | |
b7d619b0 | 1379 | assert(ht); |
0b6aa001 LJ |
1380 | assert(ht->mm == mm); |
1381 | assert(ht->bucket_at == mm->bucket_at); | |
1382 | ||
b5d6b20f | 1383 | ht->flags = flags; |
7b17c13e | 1384 | ht->flavor = flavor; |
b7d619b0 | 1385 | ht->resize_attr = attr; |
5afadd12 | 1386 | alloc_split_items_count(ht); |
abc490a1 MD |
1387 | /* this mutex should not nest in read-side C.S. */ |
1388 | pthread_mutex_init(&ht->resize_mutex, NULL); | |
5bc6b66f | 1389 | order = cds_lfht_get_count_order_ulong(init_size); |
7b3893e4 | 1390 | ht->resize_target = 1UL << order; |
1ee8f000 | 1391 | cds_lfht_create_bucket(ht, 1UL << order); |
7b3893e4 | 1392 | ht->size = 1UL << order; |
abc490a1 MD |
1393 | return ht; |
1394 | } | |
1395 | ||
6f554439 | 1396 | void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash, |
996ff57c | 1397 | cds_lfht_match_fct match, const void *key, |
6f554439 | 1398 | struct cds_lfht_iter *iter) |
2ed95849 | 1399 | { |
04db56f8 | 1400 | struct cds_lfht_node *node, *next, *bucket; |
0422d92c | 1401 | unsigned long reverse_hash, size; |
2ed95849 | 1402 | |
abc490a1 | 1403 | reverse_hash = bit_reverse_ulong(hash); |
464a1ec9 | 1404 | |
7b3893e4 | 1405 | size = rcu_dereference(ht->size); |
04db56f8 | 1406 | bucket = lookup_bucket(ht, size, hash); |
1ee8f000 | 1407 | /* We can always skip the bucket node initially */ |
04db56f8 | 1408 | node = rcu_dereference(bucket->next); |
bb7b2f26 | 1409 | node = clear_flag(node); |
2ed95849 | 1410 | for (;;) { |
8ed51e04 | 1411 | if (caa_unlikely(is_end(node))) { |
96ad1112 | 1412 | node = next = NULL; |
abc490a1 | 1413 | break; |
bb7b2f26 | 1414 | } |
04db56f8 | 1415 | if (caa_unlikely(node->reverse_hash > reverse_hash)) { |
96ad1112 | 1416 | node = next = NULL; |
abc490a1 | 1417 | break; |
2ed95849 | 1418 | } |
04db56f8 | 1419 | next = rcu_dereference(node->next); |
7f52427b | 1420 | assert(node == clear_flag(node)); |
8ed51e04 | 1421 | if (caa_likely(!is_removed(next)) |
1ee8f000 | 1422 | && !is_bucket(next) |
04db56f8 | 1423 | && node->reverse_hash == reverse_hash |
0422d92c | 1424 | && caa_likely(match(node, key))) { |
273399de | 1425 | break; |
2ed95849 | 1426 | } |
1b81fe1a | 1427 | node = clear_flag(next); |
2ed95849 | 1428 | } |
1ee8f000 | 1429 | assert(!node || !is_bucket(rcu_dereference(node->next))); |
adc0de68 MD |
1430 | iter->node = node; |
1431 | iter->next = next; | |
abc490a1 | 1432 | } |
e0ba718a | 1433 | |
0422d92c | 1434 | void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match, |
996ff57c | 1435 | const void *key, struct cds_lfht_iter *iter) |
a481e5ff | 1436 | { |
adc0de68 | 1437 | struct cds_lfht_node *node, *next; |
a481e5ff | 1438 | unsigned long reverse_hash; |
a481e5ff | 1439 | |
adc0de68 | 1440 | node = iter->node; |
04db56f8 | 1441 | reverse_hash = node->reverse_hash; |
adc0de68 | 1442 | next = iter->next; |
a481e5ff MD |
1443 | node = clear_flag(next); |
1444 | ||
1445 | for (;;) { | |
8ed51e04 | 1446 | if (caa_unlikely(is_end(node))) { |
96ad1112 | 1447 | node = next = NULL; |
a481e5ff | 1448 | break; |
bb7b2f26 | 1449 | } |
04db56f8 | 1450 | if (caa_unlikely(node->reverse_hash > reverse_hash)) { |
96ad1112 | 1451 | node = next = NULL; |
a481e5ff MD |
1452 | break; |
1453 | } | |
04db56f8 | 1454 | next = rcu_dereference(node->next); |
8ed51e04 | 1455 | if (caa_likely(!is_removed(next)) |
1ee8f000 | 1456 | && !is_bucket(next) |
04db56f8 | 1457 | && caa_likely(match(node, key))) { |
a481e5ff MD |
1458 | break; |
1459 | } | |
1460 | node = clear_flag(next); | |
1461 | } | |
1ee8f000 | 1462 | assert(!node || !is_bucket(rcu_dereference(node->next))); |
adc0de68 MD |
1463 | iter->node = node; |
1464 | iter->next = next; | |
a481e5ff MD |
1465 | } |
1466 | ||
4e9b9fbf MD |
1467 | void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) |
1468 | { | |
1469 | struct cds_lfht_node *node, *next; | |
1470 | ||
853395e1 | 1471 | node = clear_flag(iter->next); |
4e9b9fbf | 1472 | for (;;) { |
8ed51e04 | 1473 | if (caa_unlikely(is_end(node))) { |
4e9b9fbf MD |
1474 | node = next = NULL; |
1475 | break; | |
1476 | } | |
04db56f8 | 1477 | next = rcu_dereference(node->next); |
8ed51e04 | 1478 | if (caa_likely(!is_removed(next)) |
1ee8f000 | 1479 | && !is_bucket(next)) { |
4e9b9fbf MD |
1480 | break; |
1481 | } | |
1482 | node = clear_flag(next); | |
1483 | } | |
1ee8f000 | 1484 | assert(!node || !is_bucket(rcu_dereference(node->next))); |
4e9b9fbf MD |
1485 | iter->node = node; |
1486 | iter->next = next; | |
1487 | } | |
1488 | ||
1489 | void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter) | |
1490 | { | |
4e9b9fbf | 1491 | /* |
1ee8f000 | 1492 | * Get next after first bucket node. The first bucket node is the |
4e9b9fbf MD |
1493 | * first node of the linked list. |
1494 | */ | |
9d72a73f | 1495 | iter->next = bucket_at(ht, 0)->next; |
4e9b9fbf MD |
1496 | cds_lfht_next(ht, iter); |
1497 | } | |
1498 | ||
0422d92c MD |
1499 | void cds_lfht_add(struct cds_lfht *ht, unsigned long hash, |
1500 | struct cds_lfht_node *node) | |
abc490a1 | 1501 | { |
0422d92c | 1502 | unsigned long size; |
ab7d5fc6 | 1503 | |
709bacf9 | 1504 | node->reverse_hash = bit_reverse_ulong(hash); |
7b3893e4 | 1505 | size = rcu_dereference(ht->size); |
91a75cc5 | 1506 | _cds_lfht_add(ht, hash, NULL, NULL, size, node, NULL, 0); |
14360f1c | 1507 | ht_count_add(ht, size, hash); |
3eca1b8c MD |
1508 | } |
1509 | ||
14044b37 | 1510 | struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, |
6f554439 | 1511 | unsigned long hash, |
0422d92c | 1512 | cds_lfht_match_fct match, |
996ff57c | 1513 | const void *key, |
48ed1c18 | 1514 | struct cds_lfht_node *node) |
3eca1b8c | 1515 | { |
0422d92c | 1516 | unsigned long size; |
83beee94 | 1517 | struct cds_lfht_iter iter; |
3eca1b8c | 1518 | |
709bacf9 | 1519 | node->reverse_hash = bit_reverse_ulong(hash); |
7b3893e4 | 1520 | size = rcu_dereference(ht->size); |
91a75cc5 | 1521 | _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0); |
83beee94 | 1522 | if (iter.node == node) |
14360f1c | 1523 | ht_count_add(ht, size, hash); |
83beee94 | 1524 | return iter.node; |
2ed95849 MD |
1525 | } |
1526 | ||
9357c415 | 1527 | struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, |
6f554439 | 1528 | unsigned long hash, |
0422d92c | 1529 | cds_lfht_match_fct match, |
996ff57c | 1530 | const void *key, |
48ed1c18 MD |
1531 | struct cds_lfht_node *node) |
1532 | { | |
0422d92c | 1533 | unsigned long size; |
83beee94 | 1534 | struct cds_lfht_iter iter; |
48ed1c18 | 1535 | |
709bacf9 | 1536 | node->reverse_hash = bit_reverse_ulong(hash); |
7b3893e4 | 1537 | size = rcu_dereference(ht->size); |
83beee94 | 1538 | for (;;) { |
91a75cc5 | 1539 | _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0); |
83beee94 | 1540 | if (iter.node == node) { |
14360f1c | 1541 | ht_count_add(ht, size, hash); |
83beee94 MD |
1542 | return NULL; |
1543 | } | |
1544 | ||
1545 | if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node)) | |
1546 | return iter.node; | |
1547 | } | |
48ed1c18 MD |
1548 | } |
1549 | ||
2e79c445 MD |
1550 | int cds_lfht_replace(struct cds_lfht *ht, |
1551 | struct cds_lfht_iter *old_iter, | |
1552 | unsigned long hash, | |
1553 | cds_lfht_match_fct match, | |
1554 | const void *key, | |
9357c415 MD |
1555 | struct cds_lfht_node *new_node) |
1556 | { | |
1557 | unsigned long size; | |
1558 | ||
709bacf9 | 1559 | new_node->reverse_hash = bit_reverse_ulong(hash); |
2e79c445 MD |
1560 | if (!old_iter->node) |
1561 | return -ENOENT; | |
1562 | if (caa_unlikely(old_iter->node->reverse_hash != new_node->reverse_hash)) | |
1563 | return -EINVAL; | |
1564 | if (caa_unlikely(!match(old_iter->node, key))) | |
1565 | return -EINVAL; | |
7b3893e4 | 1566 | size = rcu_dereference(ht->size); |
9357c415 MD |
1567 | return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next, |
1568 | new_node); | |
1569 | } | |
1570 | ||
bc8c3c74 | 1571 | int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node) |
2ed95849 | 1572 | { |
14360f1c | 1573 | unsigned long size, hash; |
df44348d | 1574 | int ret; |
abc490a1 | 1575 | |
7b3893e4 | 1576 | size = rcu_dereference(ht->size); |
bc8c3c74 | 1577 | ret = _cds_lfht_del(ht, size, node); |
14360f1c | 1578 | if (!ret) { |
bc8c3c74 | 1579 | hash = bit_reverse_ulong(node->reverse_hash); |
14360f1c LJ |
1580 | ht_count_del(ht, size, hash); |
1581 | } | |
df44348d | 1582 | return ret; |
2ed95849 | 1583 | } |
ab7d5fc6 | 1584 | |
df55172a MD |
1585 | int cds_lfht_is_node_deleted(struct cds_lfht_node *node) |
1586 | { | |
1587 | return is_removed(rcu_dereference(node->next)); | |
1588 | } | |
1589 | ||
abc490a1 | 1590 | static |
1ee8f000 | 1591 | int cds_lfht_delete_bucket(struct cds_lfht *ht) |
674f7a69 | 1592 | { |
14044b37 | 1593 | struct cds_lfht_node *node; |
4105056a | 1594 | unsigned long order, i, size; |
674f7a69 | 1595 | |
abc490a1 | 1596 | /* Check that the table is empty */ |
9d72a73f | 1597 | node = bucket_at(ht, 0); |
abc490a1 | 1598 | do { |
04db56f8 | 1599 | node = clear_flag(node)->next; |
1ee8f000 | 1600 | if (!is_bucket(node)) |
abc490a1 | 1601 | return -EPERM; |
273399de | 1602 | assert(!is_removed(node)); |
bb7b2f26 | 1603 | } while (!is_end(node)); |
4105056a MD |
1604 | /* |
1605 | * size accessed without rcu_dereference because hash table is | |
1606 | * being destroyed. | |
1607 | */ | |
7b3893e4 | 1608 | size = ht->size; |
1ee8f000 | 1609 | /* Internal sanity check: all nodes left should be bucket */ |
48f1b16d LJ |
1610 | for (i = 0; i < size; i++) { |
1611 | node = bucket_at(ht, i); | |
1612 | dbg_printf("delete bucket: index %lu expected hash %lu hash %lu\n", | |
1613 | i, i, bit_reverse_ulong(node->reverse_hash)); | |
1614 | assert(is_bucket(node->next)); | |
1615 | } | |
24365af7 | 1616 | |
5bc6b66f | 1617 | for (order = cds_lfht_get_count_order_ulong(size); (long)order >= 0; order--) |
48f1b16d | 1618 | cds_lfht_free_bucket_table(ht, order); |
5488222b | 1619 | |
abc490a1 | 1620 | return 0; |
674f7a69 MD |
1621 | } |
1622 | ||
1623 | /* | |
1624 | * Should only be called when no more concurrent readers nor writers can | |
1625 | * possibly access the table. | |
1626 | */ | |
b7d619b0 | 1627 | int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr) |
674f7a69 | 1628 | { |
5e28c532 MD |
1629 | int ret; |
1630 | ||
848d4088 | 1631 | /* Wait for in-flight resize operations to complete */ |
24953e08 MD |
1632 | _CMM_STORE_SHARED(ht->in_progress_destroy, 1); |
1633 | cmm_smp_mb(); /* Store destroy before load resize */ | |
848d4088 MD |
1634 | while (uatomic_read(&ht->in_progress_resize)) |
1635 | poll(NULL, 0, 100); /* wait for 100ms */ | |
1ee8f000 | 1636 | ret = cds_lfht_delete_bucket(ht); |
abc490a1 MD |
1637 | if (ret) |
1638 | return ret; | |
5afadd12 | 1639 | free_split_items_count(ht); |
b7d619b0 MD |
1640 | if (attr) |
1641 | *attr = ht->resize_attr; | |
98808fb1 | 1642 | poison_free(ht); |
5e28c532 | 1643 | return ret; |
674f7a69 MD |
1644 | } |
1645 | ||
14044b37 | 1646 | void cds_lfht_count_nodes(struct cds_lfht *ht, |
d933dd0e | 1647 | long *approx_before, |
273399de | 1648 | unsigned long *count, |
d933dd0e | 1649 | long *approx_after) |
273399de | 1650 | { |
14044b37 | 1651 | struct cds_lfht_node *node, *next; |
caf3653d | 1652 | unsigned long nr_bucket = 0, nr_removed = 0; |
273399de | 1653 | |
7ed7682f | 1654 | *approx_before = 0; |
5afadd12 | 1655 | if (ht->split_count) { |
973e5e1b MD |
1656 | int i; |
1657 | ||
4c42f1b8 LJ |
1658 | for (i = 0; i < split_count_mask + 1; i++) { |
1659 | *approx_before += uatomic_read(&ht->split_count[i].add); | |
1660 | *approx_before -= uatomic_read(&ht->split_count[i].del); | |
973e5e1b MD |
1661 | } |
1662 | } | |
1663 | ||
273399de | 1664 | *count = 0; |
273399de | 1665 | |
1ee8f000 | 1666 | /* Count non-bucket nodes in the table */ |
9d72a73f | 1667 | node = bucket_at(ht, 0); |
273399de | 1668 | do { |
04db56f8 | 1669 | next = rcu_dereference(node->next); |
b198f0fd | 1670 | if (is_removed(next)) { |
1ee8f000 | 1671 | if (!is_bucket(next)) |
caf3653d | 1672 | (nr_removed)++; |
973e5e1b | 1673 | else |
1ee8f000 LJ |
1674 | (nr_bucket)++; |
1675 | } else if (!is_bucket(next)) | |
273399de | 1676 | (*count)++; |
24365af7 | 1677 | else |
1ee8f000 | 1678 | (nr_bucket)++; |
273399de | 1679 | node = clear_flag(next); |
bb7b2f26 | 1680 | } while (!is_end(node)); |
caf3653d | 1681 | dbg_printf("number of logically removed nodes: %lu\n", nr_removed); |
1ee8f000 | 1682 | dbg_printf("number of bucket nodes: %lu\n", nr_bucket); |
7ed7682f | 1683 | *approx_after = 0; |
5afadd12 | 1684 | if (ht->split_count) { |
973e5e1b MD |
1685 | int i; |
1686 | ||
4c42f1b8 LJ |
1687 | for (i = 0; i < split_count_mask + 1; i++) { |
1688 | *approx_after += uatomic_read(&ht->split_count[i].add); | |
1689 | *approx_after -= uatomic_read(&ht->split_count[i].del); | |
973e5e1b MD |
1690 | } |
1691 | } | |
273399de MD |
1692 | } |
1693 | ||
1475579c | 1694 | /* called with resize mutex held */ |
abc490a1 | 1695 | static |
4105056a | 1696 | void _do_cds_lfht_grow(struct cds_lfht *ht, |
1475579c | 1697 | unsigned long old_size, unsigned long new_size) |
abc490a1 | 1698 | { |
1475579c | 1699 | unsigned long old_order, new_order; |
1475579c | 1700 | |
5bc6b66f MD |
1701 | old_order = cds_lfht_get_count_order_ulong(old_size); |
1702 | new_order = cds_lfht_get_count_order_ulong(new_size); | |
1a401918 LJ |
1703 | dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", |
1704 | old_size, old_order, new_size, new_order); | |
1475579c | 1705 | assert(new_size > old_size); |
93d46c39 | 1706 | init_table(ht, old_order + 1, new_order); |
abc490a1 MD |
1707 | } |
1708 | ||
1709 | /* called with resize mutex held */ | |
1710 | static | |
4105056a | 1711 | void _do_cds_lfht_shrink(struct cds_lfht *ht, |
1475579c | 1712 | unsigned long old_size, unsigned long new_size) |
464a1ec9 | 1713 | { |
1475579c | 1714 | unsigned long old_order, new_order; |
464a1ec9 | 1715 | |
d0d8f9aa | 1716 | new_size = max(new_size, MIN_TABLE_SIZE); |
5bc6b66f MD |
1717 | old_order = cds_lfht_get_count_order_ulong(old_size); |
1718 | new_order = cds_lfht_get_count_order_ulong(new_size); | |
1a401918 LJ |
1719 | dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", |
1720 | old_size, old_order, new_size, new_order); | |
1475579c | 1721 | assert(new_size < old_size); |
1475579c | 1722 | |
1ee8f000 | 1723 | /* Remove and unlink all bucket nodes to remove. */ |
93d46c39 | 1724 | fini_table(ht, new_order + 1, old_order); |
464a1ec9 MD |
1725 | } |
1726 | ||
1475579c MD |
1727 | |
1728 | /* called with resize mutex held */ | |
1729 | static | |
1730 | void _do_cds_lfht_resize(struct cds_lfht *ht) | |
1731 | { | |
1732 | unsigned long new_size, old_size; | |
4105056a MD |
1733 | |
1734 | /* | |
1735 | * Resize table, re-do if the target size has changed under us. | |
1736 | */ | |
1737 | do { | |
d2be3620 MD |
1738 | assert(uatomic_read(&ht->in_progress_resize)); |
1739 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) | |
1740 | break; | |
7b3893e4 LJ |
1741 | ht->resize_initiated = 1; |
1742 | old_size = ht->size; | |
1743 | new_size = CMM_LOAD_SHARED(ht->resize_target); | |
4105056a MD |
1744 | if (old_size < new_size) |
1745 | _do_cds_lfht_grow(ht, old_size, new_size); | |
1746 | else if (old_size > new_size) | |
1747 | _do_cds_lfht_shrink(ht, old_size, new_size); | |
7b3893e4 | 1748 | ht->resize_initiated = 0; |
4105056a MD |
1749 | /* write resize_initiated before read resize_target */ |
1750 | cmm_smp_mb(); | |
7b3893e4 | 1751 | } while (ht->size != CMM_LOAD_SHARED(ht->resize_target)); |
1475579c MD |
1752 | } |
1753 | ||
abc490a1 | 1754 | static |
ab65b890 | 1755 | unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size) |
464a1ec9 | 1756 | { |
7b3893e4 | 1757 | return _uatomic_xchg_monotonic_increase(&ht->resize_target, new_size); |
464a1ec9 MD |
1758 | } |
1759 | ||
1475579c | 1760 | static |
4105056a | 1761 | void resize_target_update_count(struct cds_lfht *ht, |
b8af5011 | 1762 | unsigned long count) |
1475579c | 1763 | { |
d0d8f9aa | 1764 | count = max(count, MIN_TABLE_SIZE); |
747d725c | 1765 | count = min(count, ht->max_nr_buckets); |
7b3893e4 | 1766 | uatomic_set(&ht->resize_target, count); |
1475579c MD |
1767 | } |
1768 | ||
1769 | void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size) | |
464a1ec9 | 1770 | { |
4105056a | 1771 | resize_target_update_count(ht, new_size); |
7b3893e4 | 1772 | CMM_STORE_SHARED(ht->resize_initiated, 1); |
7b17c13e | 1773 | ht->flavor->thread_offline(); |
1475579c MD |
1774 | pthread_mutex_lock(&ht->resize_mutex); |
1775 | _do_cds_lfht_resize(ht); | |
1776 | pthread_mutex_unlock(&ht->resize_mutex); | |
7b17c13e | 1777 | ht->flavor->thread_online(); |
abc490a1 | 1778 | } |
464a1ec9 | 1779 | |
abc490a1 MD |
1780 | static |
1781 | void do_resize_cb(struct rcu_head *head) | |
1782 | { | |
1783 | struct rcu_resize_work *work = | |
1784 | caa_container_of(head, struct rcu_resize_work, head); | |
14044b37 | 1785 | struct cds_lfht *ht = work->ht; |
abc490a1 | 1786 | |
7b17c13e | 1787 | ht->flavor->thread_offline(); |
abc490a1 | 1788 | pthread_mutex_lock(&ht->resize_mutex); |
14044b37 | 1789 | _do_cds_lfht_resize(ht); |
abc490a1 | 1790 | pthread_mutex_unlock(&ht->resize_mutex); |
7b17c13e | 1791 | ht->flavor->thread_online(); |
98808fb1 | 1792 | poison_free(work); |
848d4088 MD |
1793 | cmm_smp_mb(); /* finish resize before decrement */ |
1794 | uatomic_dec(&ht->in_progress_resize); | |
464a1ec9 MD |
1795 | } |
1796 | ||
abc490a1 | 1797 | static |
f1f119ee | 1798 | void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht) |
ab7d5fc6 | 1799 | { |
abc490a1 MD |
1800 | struct rcu_resize_work *work; |
1801 | ||
4105056a MD |
1802 | /* Store resize_target before read resize_initiated */ |
1803 | cmm_smp_mb(); | |
7b3893e4 | 1804 | if (!CMM_LOAD_SHARED(ht->resize_initiated)) { |
848d4088 | 1805 | uatomic_inc(&ht->in_progress_resize); |
59290e9d | 1806 | cmm_smp_mb(); /* increment resize count before load destroy */ |
ed35e6d8 MD |
1807 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) { |
1808 | uatomic_dec(&ht->in_progress_resize); | |
59290e9d | 1809 | return; |
ed35e6d8 | 1810 | } |
f9830efd | 1811 | work = malloc(sizeof(*work)); |
741f378e MD |
1812 | if (work == NULL) { |
1813 | dbg_printf("error allocating resize work, bailing out\n"); | |
1814 | uatomic_dec(&ht->in_progress_resize); | |
1815 | return; | |
1816 | } | |
f9830efd | 1817 | work->ht = ht; |
7b17c13e | 1818 | ht->flavor->update_call_rcu(&work->head, do_resize_cb); |
7b3893e4 | 1819 | CMM_STORE_SHARED(ht->resize_initiated, 1); |
f9830efd | 1820 | } |
ab7d5fc6 | 1821 | } |
3171717f | 1822 | |
f1f119ee LJ |
1823 | static |
1824 | void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth) | |
1825 | { | |
1826 | unsigned long target_size = size << growth; | |
1827 | ||
747d725c | 1828 | target_size = min(target_size, ht->max_nr_buckets); |
f1f119ee LJ |
1829 | if (resize_target_grow(ht, target_size) >= target_size) |
1830 | return; | |
1831 | ||
1832 | __cds_lfht_resize_lazy_launch(ht); | |
1833 | } | |
1834 | ||
89bb121d LJ |
1835 | /* |
1836 | * We favor grow operations over shrink. A shrink operation never occurs | |
1837 | * if a grow operation is queued for lazy execution. A grow operation | |
1838 | * cancels any pending shrink lazy execution. | |
1839 | */ | |
3171717f | 1840 | static |
4105056a | 1841 | void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, |
3171717f MD |
1842 | unsigned long count) |
1843 | { | |
b8af5011 MD |
1844 | if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) |
1845 | return; | |
d0d8f9aa | 1846 | count = max(count, MIN_TABLE_SIZE); |
747d725c | 1847 | count = min(count, ht->max_nr_buckets); |
89bb121d LJ |
1848 | if (count == size) |
1849 | return; /* Already the right size, no resize needed */ | |
1850 | if (count > size) { /* lazy grow */ | |
1851 | if (resize_target_grow(ht, count) >= count) | |
1852 | return; | |
1853 | } else { /* lazy shrink */ | |
1854 | for (;;) { | |
1855 | unsigned long s; | |
1856 | ||
7b3893e4 | 1857 | s = uatomic_cmpxchg(&ht->resize_target, size, count); |
89bb121d LJ |
1858 | if (s == size) |
1859 | break; /* no resize needed */ | |
1860 | if (s > size) | |
1861 | return; /* growing is/(was just) in progress */ | |
1862 | if (s <= count) | |
1863 | return; /* some other thread do shrink */ | |
1864 | size = s; | |
1865 | } | |
1866 | } | |
f1f119ee | 1867 | __cds_lfht_resize_lazy_launch(ht); |
3171717f | 1868 | } |